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🧵 Untitled Thread

Anonymous No. 16416846

Does anyone here understand string theory?

Anonymous No. 16416909

>>16416846
It's not a real scientific theory (testable). It's made up bullshit.

Anonymous No. 16416921

>>16416909
so that's a no, anyone else?

Anonymous No. 16416922

>>16416846
Yes

>>16416909
It is testable, we just can't test it.

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Anonymous No. 16416951

>>16416922

Anonymous No. 16417033

>>16416922
kek

Anonymous No. 16417039

>>16416922
Anon, I…

Anonymous No. 16417040

>>16416846
Yes. String scientist here. Most in my field agree that smallest particles aren't actually smallest and they are composed of even smaller string which go beyond planck scale, down to the literal pixel of our universe. Those strings so tiny they van travel between dimensions at light speed and be at multiple places at once. Recent observations suggest that there exist on big (hence very small and very long) parent string responsible for acceleration of our universe.

Anonymous No. 16417046

>>16417040
Hello, Mr string scientist. Please explain what a Virasoro algebra is.

Anonymous No. 16417050

>>16417046
Just google it ain't gonna waste my time explaining stuff. Better ask questions that wikipedia does not know answers to. Or maybe become physicist?

Anonymous No. 16417051

>>16417050
Ah, thank you. You did not pass the pseud litmus test, Mr Pseud.

Anonymous No. 16417052

>>16417046
The **Virasoro algebra** is a central concept in theoretical physics and mathematics, especially in the study of conformal field theory and string theory. It is a Lie algebra that is closely related to the group of conformal transformations in two dimensions.

### Definition
The Virasoro algebra is an infinite-dimensional Lie algebra generated by a set of operators \( L_n \) (where \( n \) is an integer), which satisfy the following commutation relations:

\[
[L_m, L_n] = (m - n) L_{m+n} + \frac{c}{12} (m^3 - m) \delta_{m+n, 0} \, I
\]

Here:

- \( L_n \) are the generators of the algebra (often called "mode operators").
- \( c \) is a constant known as the **central charge**. It measures the "size" of the algebra and can be thought of as a measure of the anomaly in the theory. For instance, in string theory, the central charge is related to the number of dimensions of the spacetime.
- \( \delta_{m+n, 0} \) is the Kronecker delta function, which ensures that the central term appears only when \( m + n = 0 \).

### Intuition
- The Virasoro algebra can be thought of as an extension of the ordinary Lie algebra of generators, with an extra "central extension" term that reflects the subtleties of the infinite-dimensional structure.
- The generators \( L_n \) typically correspond to infinitesimal transformations in the conformal group (translations, rotations, and dilations) and their higher-order versions, corresponding to the generators of a larger symmetry group.

Anonymous No. 16417053

>>16417046
>>16417052
### Conformal Transformations
The Virasoro algebra governs the symmetries of a two-dimensional conformal field theory. It generalizes the finite-dimensional Lie algebra of the conformal group (which consists of transformations such as translations, rotations, and scaling in 2D space) to an infinite number of generators, corresponding to the infinite series of conformal transformations.

### Central Charge and Representations
- The central charge \( c \) is crucial in the classification of different conformal field theories. It determines the structure of the representations of the Virasoro algebra.
- In physical theories, the representation space of the Virasoro algebra typically consists of states (or fields) that transform under these symmetry generators. The representations can be classified by the value of \( c \) and the so-called "primary states" (or primary fields), which are states that transform in a specific way under the generators.

### Applications
- **Conformal Field Theory (CFT):** The Virasoro algebra plays a central role in the study of CFT, where it governs the symmetries of the theory.
- **String Theory:** In the quantization of strings, the Virasoro algebra arises naturally from the analysis of the string's vibrations, which leads to an infinite-dimensional symmetry algebra. The central charge \( c \) also plays a key role in determining the consistency of the theory.
- **Statistical Mechanics and Black Hole Physics:** The Virasoro algebra has connections to statistical mechanics, particularly in the study of the entropy of black holes (through the holographic principle).

In summary, the Virasoro algebra is a key mathematical structure in the study of two-dimensional quantum systems, capturing the symmetries of conformal transformations with an infinite-dimensional extension.

Anonymous No. 16417054

>>16417052
Wow, thank you. A “string scientist” sure can’t explain something in their own words and copypastes wikipedia articles.

Anonymous No. 16417055

>>16417040
.cont

String is negative dimensional object looking from outside. And this outside is our universe. It is embeded into the core machinery of non-zero pixelation of reality. When it interacts with other strings it produces two things. Quarks and fields. Quarks make up atoms and so on but generally important thing is field which hold everything together. By extending and contracting a string is able to move as centipede but at light speed. Some my coworkers believe they move even faster than that but it's to be tested yet.

Anonymous No. 16417057

>>16417054
Cope. I answered your question and now you're shifting goalposts.

Anonymous No. 16417058

>>16417055
>Some my coworkers believe
Your coworkers are too busy scamming grandmas, rajesh

Anonymous No. 16417059

>>16417054
Don't ask questions you know answers to. It's a sign of schizos. If you want to learn more you can sign up to my newsletter, we have over 200 participants.

Anonymous No. 16417061

>>16417057
You didn’t do it in your own words. If you ask me to explain something gauge theory related, I can do it without wikipedia. That’s what an actual scientist does.

Anonymous No. 16417062

>>16417061
None of that is from wikipedia. Cope harder

Anonymous No. 16417065

>>16417062
https://en.wikipedia.org/wiki/Virasoro_algebra
You probably used ChatGPT which copied things from wikipedia kek. Great science saar, please use more AI to get results you bloody.

Anonymous No. 16417067

>>16417065
Way to derail the thread. String theory may be not for you if you are stuck with first grade math

Anonymous No. 16417073

>>16417067
It’s not for me because it cannot produce testable predictions. Still waiting for those SM parameter derivations stringniggers promised in the 90s.

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Anonymous No. 16417106

>>16416846 here you go

Anonymous No. 16417127

>>16417073
Then ask questions, if you are over 18 years old and not just teenage larper>>16417106

Anonymous No. 16417294

Is string theory basically just Pure Maths for people who aren’t great at math? Or is it more Applied Maths for people who don’t know what Applied means?

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Anonymous No. 16417395

It's not a unworthy or bad theory it's just nearly impossible to verify.

Anonymous No. 16417500

>>16417127
>Then ask questions
Where are the SM parameter predictions you niggers promised 30 years ago? I’m waiting.

🗑️ Anonymous No. 16417793

>>16416846
Yes, more or less. I work in a closely related field of theoretical physics. What do you want to know?

>Please explain what a Virasoro algebra is
It's a symmetry algebra obeyed by the generators of 2D conformal symmetry. It's relevant to string theory because the theory on the worldsheet of a string ought to have conformal symmetry after gauge fixing the worldsheet metric (moreover it ought to have a particular value of the central charge in order to cancel the conformal anomaly).

>>16417294
>Where are the SM parameter predictions you niggers promised 30 years ago?
People were more optimistic that string theory would be a theory of everything 30 years ago. That's not how most theorists understand it today. Understanding string theory doesn't mean you subscribe to the idea that everything is fundamental strings.

Anonymous No. 16417795

>>16416846 (OP)
Yes, more or less. I work in a closely related field of theoretical physics. What do you want to know?

>>16417046
>Please explain what a Virasoro algebra is
It's a symmetry algebra obeyed by the generators of 2D conformal symmetry. It's relevant to string theory because the theory on the worldsheet of a string ought to have conformal symmetry after gauge fixing the worldsheet metric (moreover it ought to have a particular value of the central charge in order to cancel the conformal anomaly).

>>16417500
>Where are the SM parameter predictions you niggers promised 30 years ago?
People were more optimistic that string theory would be a theory of everything 30 years ago. That's not how most theorists understand it today. Understanding string theory doesn't mean you subscribe to the idea that everything is fundamental strings.

Anonymous No. 16417827

>>16417795
>That's not how most theorists understand it today
Ah, yes, the “framework” cope. What has string theory done to vanilla gauge theory? Aside from vacuuming funds from non-stringy people?

Anonymous No. 16417866

>>16417827
>What has string theory done to vanilla gauge theory?
One example: Figure out the correlator of two Wilson lines in ordinary 4D Yang-Mills theory from the lattice. You can extract energy eigenvalues from this correlation function in the same way as you can from a correlation function of local operators. It turns out these energy eigenvalues are closely given by the spectrum of a free bosonic string in 4 spacetime dimensions (not 26). So basically the formula for the spectrum which is calculated in Polchinski's textbook is appearing in the "real" world. (This is pure Yang-Mills without quarks so I put "real" in quotes, but this is pretty close.)

Anonymous No. 16417879

>>16417866
hahahah so these practical applications are just the ones you had in the 70s back when it was competing with QCD instead of being the schizo amateur math bubble it is now? Bitch, please.

Anonymous No. 16417894

>>16417879
This isn't from the 70s. It is from 10 years ago. It maybe could have been done in the 70s, but people did not understand how effective string theory worked then, and the lattice results were not at the appropriate level to give the hint then.

Anonymous No. 16417924

>>16417894
All I’m saying is, we’ve gone full circle. It’s really fucking funny.
>come up with a theory to explain the strong force
>turns out it only works in 26 dimensions and has tachyonic states
>QCD is a much less complicated theory that explains the strong force just fine
>decide to put susy into it because it’s in vogue
>”bro, we have the supertheory of supereverything, this is it!”
>discover it’s actually five and there’s no way of knowing which one it is
>Dr Egghead comes in and mumbles something about M-theory even though no one understands
>”bro, we can derive Hawking radiation from string theory”
>the cosmological constant is measured to be positive
>find out that your bullshit has a gazillion compactifications with no way of choosing one
>”it’s ackhuyally not that important that we derive the SM representations from this, bro, I swear”
>still no proof that gravity is renormalizable in string theory
>”bro, it just works. Trust me, bro, you’re just too stupid to understand. I had a vision about it while huffing my august high IQ farts! It’s renormalizable, totally!”
>LHC finds no evidence of minimal SUSY
>”actually bro string theory isn’t actually a theory of everything, bro. It’s a framework that will help us understand gauge theory!”
>proceeds to produce some extremely obscure results in Yang-Mills theory that could have probably been derived without having to spend 50 years on amateur math
what a massive L for stringniggers. But worst of all, it has irreparably damaged the HEP reputation as laymen now think we’re all crackpots living in our 11 dimension playing harps instead of doing work.

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Anonymous No. 16417926

>>16416922

Anonymous No. 16417932

>>16417065
>Applications: String theory
Does nobody know what an application is anymore? By this argument, number theory is applied math since you can apply theorems to certain areas of number theory.

Anonymous No. 16417943

>>16417866
>I put "real" in quotes, but this is pretty close
Kek. So this is how string fags cope now

Anonymous No. 16417962

>>16417924
Yeah historically it's gone full circle. The discovery that the low lying states of strings included gravitons sidelined the more physical applications to gauge theories and people got (justifiably, in my opinion) excited that it might be a bigger deal than it was. But the whole string phenomenology program got dragged down by the landscape issue and that program is pretty much dead except for a few people working on "swampland" stuff.

By the way, I think you are mistaken in saying that gravity in string theory is not renormalizable. You can calculate S-matrix elements of gravitons and there are no UV divergences, so it's not clear to me what you are even thinking of.

Anonymous No. 16417964

>>16417943
You don't even understand what we're talking about.

Anonymous No. 16417973

lol

Anonymous No. 16417986

>>16417962
>Yeah historically it's gone full circle
If that’s the case, I personally would only take it seriously if it produces something truly worth of all that fuss like the explanation of the strong CP problem. Until then, I doubt people need to spend a decade on something so specialized just to produce obscure results that have a ton of asterisks attached. You mentioned in your post how the calculation only works for pure Yang-Mills. Even having the barest understanding of string theory, I know for a fact that you can’t extend it to Yang-Mills coupled to fermions without involving supersymmetry. So this derivation isn’t fruitful at all.
>By the way, I think you are mistaken in saying that gravity in string theory is not renormalizable. You can calculate S-matrix elements of gravitons and there are no UV divergences
That’s pure gravity. It’s also renormalizable in GR up to, but not including, two loops. But the moment you couple it to anything else, it diverges at one loop already. So my question is, are string theorists one hundred percent certain that gravitons coupled to every single state their crap produces result in a renormalizable theory? Is there a specific paper you could link?

Anonymous No. 16417989

>>16417964
String theory either describes reality or it doesn't. That you dodge such a simple question is telling.

Anonymous No. 16418019

>>16417986
>I know for a fact that you can’t extend it to Yang-Mills coupled to fermions without involving supersymmetry. So this derivation isn’t fruitful at all.
I don't think you know what you think you do. The idea is that mesons with quarks are just open strings with the same sort of string theory that appears in Yang-Mills (which involves only closed strings). There doesn't need to be SUSY anywhere.

>>16417986
>So my question is, are string theorists one hundred percent certain that gravitons coupled to every single state their crap produces result in a renormalizable theory? Is there a specific paper you could link?

The crap their theory produces is all a bunch of things like the antisymmetric B field or dilaton, which you might be familiar with if you have learned some basic string theory. If you write it as a field theory you end up with something that looks like an effective field theory, where the lowest order term involves the Einstein-Hilbert action and the action for the B-field (which looks a lot like the action for an ordinary gauge field there's just an extra index). And then there is in principle an infinite series of additional contributions to the action which involve extra derivatives (these have been calculated to maybe the next order or two in practice). This is renormalizable in the same way any effective field theory is.

But you don't need the effective field theory to prove renormalizability. The goal of the effective field theory is to calculate scattering amplitudes. You can calculate these directly from the CFT on the worldsheet and this is what most of a string theory textbook teaches.

Anonymous No. 16418038

>>16417989
Yang-Mills is the theory of gluons, which exist in the real world. The work I am describing is isolating this theory of gluons and attempting to understand it first. It is not always useful to try to understand everything at once.

Anonymous No. 16418048

>>16418019
>There doesn't need to be SUSY anywhere.
Isn’t susy the necessary component of producing fermionic strings? I thought “regular” non-susy strings can only be bosonic.
> This is renormalizable in the same way any effective field theory is.
??? Fermi theory isn’t renormalizable. And you still haven’t answered my question. I asked you about couplings for a very good reason. For a long time people thought pure sugra was renormalizable, until it turned out to diverge at something crazy like 6 or 8 loops. But coupled sugra already diverges at 2 or 3. Gravity seems to really dislike being coupled to things. So I want to see an argument as to how gravity is renormalized not just on its own, but with matter terms present in the action.

Anonymous No. 16418079

>>16418048
>Isn’t susy the necessary component of producing fermionic strings?
A meson has zero fermion number, and that's what I am describing. I don't know whether baryons can be described in a purely stringy way in this framework.

>Fermi theory isn’t renormalizable.
The divergences in loops of the Fermi theory take the form of some higher dimension local operator, so you add those operators to your action at next order, and then you can make sense of the loop corrections to the Fermi theory. The effective theory of gravity works the same way. In general you get new parameters you have to specify at each order.

My point is this whole effective field theory scheme is a way to calculate scattering amplitudes. In string theory you can just calculate the scattering amplitudes from the beginning and there are no divergences. You can find the effective field theory that leads to the same scattering amplitudes and it is indeed the effective theory of gravity with the coefficients specified (and you can get the same effective theory from the string sigma model).

Anonymous No. 16418093

>>16418048
Also I just found a paper reference if you'd like to see (although I don't know if it will be understandable). It is Metsaev, Tseytlin in 1987 (doi.org/10.1016/0550-3213(87)90077-0). They are basically calculating the higher order terms in the action (the terms that cancel the divergences in loops of the classical action) two ways, one by matching to scattering amplitudes and one by considering the string sigma model.

Anonymous No. 16418096

>>16418079
>A meson has zero fermion number, and that's what I am describing.
Yeah, I know. So you're still limiting yourselves without a way out. Your result only concerns integral spin fields. Too bad the overwhelming majority of observed matter is baryonic.
>I don't know whether baryons can be described in a purely stringy way in this framework.
They can't, which is what I alluded to. You had initially said quarks btw, but now you sneakily turned them into mesons.
>My point is this whole effective field theory scheme is a way to calculate scattering amplitudes.
So are you sure that you can calculate scattering amplitudes when all matter fields are coupled to gravitons? Stop evading the question.

Anonymous No. 16418101

>>16418093
What I get from the abstract is
1. It only involves gravity-related states. No matter couplings.
2. It's only at two-loops. I want to see evidence that it's fully renormalizable, not to this or that order.

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Anonymous No. 16418103

>>16416922

Anonymous No. 16418112

>>16418096
Take my answers in good faith please. I am trying to explain how this works out to you, but you have already convinced yourself it is impossible.

>Too bad the overwhelming majority of observed matter is baryonic.
So what? The goal of that program is to describe confining strings in gauge theory, not to describe every aspect of gauge theory in terms of strings. Baryons can be understood as in the Skyrme point of view if you like.

>So are you sure that you can calculate scattering amplitudes when all matter fields are coupled to gravitons? Stop evading the question.
I'm not evading the question. I said from the beginning yes, it can. But the matter fields are the exotic fields that come with string theory and not any arbitrary fields.

Anonymous No. 16418115

>>16418101
>1. It only involves gravity-related states. No matter couplings.
The title says "Dependence on the dilaton and the antisymmetric tensor." The dilaton and antisymmetric tensor are the matter fields. The dilaton is basically a massless scalar field, and the antisymmetric tensor is a lot like a Maxwell electromagnetic tensor but the field strength is a three form instead of a two form.

Anonymous No. 16418116

>>16418112
I have not and don’t put words in my mouth. Science isn’t a religion and everything is open to debate.
>So what?
Your result is very limited with no possibility of extending it. I don’t care about pure Yang-Mills or Yang-Mills with scalars as a phenomenologist, because I expect baryonic contributions to measurements in experiments. Your theory not only doesn’t derive them but admits it can’t. If I want to extend it, I’d need something completely unrelated, probably just the good old lattice QCD. It’s like that Spongebob episode where he draws a circle by drawing a face first and erasing everything until he has a circle.
>I said from the beginning yes, it can
And is it “it can at *insert current number of loops calculated*” or is it “it can at an arbitrary order in perturbation theory”?

Anonymous No. 16418135

>>16416909
Not really, we only need to master some technological requirements before properly unlocking string theory.

Anonymous No. 16418137

>>16418135
Fag shut up

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Anonymous No. 16418139

>>16418135

Anonymous No. 16418144

>>16418116
Well don't put the words "everything is reducible to string theory" in my mouth either. I told you a result you didn't know where something in Yang-Mills theory is calculable from string theory. I am trying to show that string theory is connected to the real world. You were no doubt aware that there has long been a more or less vague idea that there are real confining strings in gauge theory, and I am letting you know that the theory has developed to the point where there is quantitative results.

As far as the renormalizable quantum gravity discussion (which is a completely seperate issue) is concerned, I am trying to explain to you that yes you can indeed calculate scattering amplitudes at an arbitrary order of perturbation theory and there will be no UV divergences. In practice of course this has only been done to a certain number of loops, just like perturbative calculations in any given renormalizable QFT have been done to a given order, even though we know in principle how to go to any order. What I don't think you are appreciating is that the calculation is done using string theory where you integrate a bunch of vertex operators over a worldsheet. You can match the calculation to an EFT of gravity and some exotic matter fields but the calculation need not be performed using the EFT. That is why I am so certain renormalization is not needed.

Anonymous No. 16418180

>>16418144
>I am trying to show that string theory is connected to the real world
the real world has fermions. Even if string theory manages to produce something that trivializes calculations for bosonic theories (say a non-perturbative amplitude), fermions would act as a bottleneck to irl amplitude calculations and we’re back to square one. It would save us a lot of trouble, I admit.
>you can indeed calculate scattering amplitudes at an arbitrary order of perturbation theory and there will be no UV divergences. In practice of course this has only been done to a certain number of loops
so is there a proof for arbitrary order?
>What I don't think you are appreciating is that the calculation is done using string theory where you integrate a bunch of vertex operators over a worldsheet
meh, it could have been done using Grothendieck-TeichmĂĽller groups or whatever super obscure thing there is in math. All I care about is pheno predictions.
>That is why I am so certain renormalization is not needed.
You are certain or you know 100%?

Anonymous No. 16418221

>>16418180
Take a look at chapter 7.3 in Polchinski if you genuinely want to understand this. He compares a one-loop calculation in string theory to the corresponding one in ordinary field theory, and the mathematical expressions are very similar, but in the string theory case the region of integration leading to the UV divergences in the field theory case is absent. He then claims this is true for higher order scattering amplitudes too. This is what I am referring to when I say there are no UV divergences in scattering amplitudes from the very beginning in string theory.

Now I am not an expert in string perturbation theory so I am not 100% sure on this, but I have seen how there are no UV divergences in some simple amplitudes (like in that chapter 7.3) and it is plausible to me that the people actually doing the calculations are telling the truth when they say there are no UV divergences in the higher ones.

Anonymous No. 16418236

>>16418221
>He then claims this is true for higher order scattering amplitudes too
Does he prove it thougheveralbeit?
>it is plausible to me that the people actually doing the calculations are telling the truth when they say there are no UV divergences in the higher ones
ah, the famous proof by authority. It's true because I said so. Or even better, it's true because I believe it is. Quad erat demonstrandum.

Anonymous No. 16418247

>>16418236
Oh please. If neither of us has done the calculation to all orders but I can show how a UV divergence is avoided at low order (even when it is present in field theory), and quote someone who has done the calculation making the claim that they never appear, then who do you believe?

This is what I meant by "if you genuinely want to understand this" and "take me in good faith." You clearly just want to argue. I am 100% playing defense in this thread, while you are just saying "nuh uh," so forgive me if I don't know every detail of a calculation in a theory I don't even work in.

Anonymous No. 16418257

>>16418247
>Defending a theory he hasn't validated
Why?

Anonymous No. 16418269

>>16418247
>quote someone who has done the calculation
You said he claimed it. Claiming and proving are very different things.
>You clearly just want to argue.
Yes, that's what science is about. And you may be right. In that case your defense is good for string theory's image. Lurkers ITT can make their own conclusions and side with you.

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Anonymous No. 16418307

I didn't understand this thread in the slightest, but I googled enough to believe this is a real conversation and not two schizos ranting at each other

Anonymous No. 16418313

>>16416846
It is just trying to find a mathematical abstraction that is homomorphic to some manifold. Strings, holographic planes, fractal symmetries, etc are all just an attempt at a sufficient description, but not necessarily the underlying structure. Just an isomorphism. And obviously, this is preferred from a modeling standpoint as mathematics leverages a logic that is burdensome to the glorified technician, the theoretician.

Anonymous No. 16418328

>>16418313
Which is higher in the intellectual hierarchy, physics(attempting to understand the universe) or math(attempting to understand all patterns in an abstract sense)

Anonymous No. 16418367

>>16417924
> But worst of all, it has irreparably damaged the HEP reputation as laymen now think we’re all crackpots living in our 11 dimension playing harps instead of doing work.
Wait, you mean you aren’t doing that?

Anonymous No. 16418369

Only 3 men have ever truly understood string theory. 2 are dead, the 3rd is in a mental institution.

raphael No. 16418433

string theory is just an infinite regress of bullshit

Anonymous No. 16418445

>>16416846
You just need 10 billion spatial dimensions, deeply logical

Anonymous No. 16418599

>>16417924
xtring xisters..

Anonymous No. 16418947

>>16416846
Who cares. It was all memes